public MapDetailsViewModel GetMapDetailsViewModel(MapFilter filter)
        {
            var startDate = DateTime.Parse(filter.StartDate);
            var endDate   = DateTime.Parse(filter.EndDate);
            var city      = _core.GetCityFilter(filter.City);

            if (city == null)
            {
                return(null);
            }

            var spotIds      = _core.GetEventSpots(city, startDate, endDate);
            var addresses    = _core.GetAddressesFromSpots(spotIds);
            var geolocations = _core.GetGeoLocations(addresses);

            var centerGeolocation = _core.GetGeoLocation(city);

            return(new MapDetailsViewModel
            {
                Geolocations = geolocations,
                CenterPosition = centerGeolocation
            });
        }